Protocol design is popular "these days" so everyone eventually chooses UDP, and reimplements a subset of TCP in their own protocol. (edit: not everyone needs state in their protocol, but everyone needs to implement rate limiting)

If you're unaware of a large interest in protocol design, or don't understand the cost and complexity of DDoS attacks, what point were you looking for?

The information density seems uncharacteristically light to me (compared to other Vixie articles).

If Vixie can simplify his message to Stallman-level clarity, how would that be a bad thing?